With an increasing requirement for accessing the Internet by a wireless device, a requirement for a radio packet data service also increases. In order to provide the wireless device with greater bandwidth, higher security, and wider coverage, an Evolution-Data Optimized (EVDO) technology appears and is widely applied.
Generally, in the EVDO technology, a base station provides multiple frequency channel numbers. In the EVDO technology, to keep load balance among frequency channel numbers, the base station maintains approximately equal quantities of access terminals camping on the frequency channel numbers. Therefore, an access terminal obtains, using a hash algorithm the same as that used by the base station, an expected frequency channel number, as a monitoring frequency channel number, from a frequency channel number list delivered by the base station. Further, one or more frequency channel numbers are provided in the frequency channel number list delivered by the base station, and the access terminal obtains, from the one or more frequency channel numbers provided in the frequency channel number list, a frequency channel number that may be expected to serve as the monitoring frequency channel number, that is, the expected frequency channel number, and then switches a monitoring frequency channel number of the access terminal to the expected frequency channel number.
In the other approaches, however, if an expected frequency channel number obtained by an access terminal is different from a frequency channel number of a signal currently received by the access terminal, namely, a current frequency channel number, the access terminal switches to the expected frequency channel number, that is, the access terminal switches a monitoring frequency channel number to the expected frequency channel number. For reasons such as incomplete network coverage, a problem such as poor signal coverage may exist in the expected frequency channel number obtained by the access terminal. As a result, the access terminal fails to switch the monitoring frequency channel number, and the access terminal repeatedly attempts to switch the frequency channel number. In this case, an EVDO service of the access terminal is unavailable. It can be learned that a technical problem of EVDO service unavailability caused by a failure to switch a monitoring frequency channel number exists in the other approaches.